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The present invention relates generally to a combined variable transmission (C.V.T.) system of a beach motor scooter, or three-wheeled motor scooter for the physically-handicapped person, and more particularly to a reverse gear device of the combined variable transmission system.
The conventional reverse gear device of the three-wheeled motor scooter is similar in design to that of the automobile and is formed of a plurality of shafts and gears. In the forward operation, the drive gear of a drive shaft actuates the driven gear. However, the driven gear does not transmit directly the power to a driven shaft. The transmission of the power is instead carried out by a wheel hub capable of axial engagement and disengagement. In another words, the wheel hub acts as a transmission medium. When a reverse operation of the driven shaft is called for, another set of three transmission gears is involved such that an idle gear is in operation to cause the driven gear to turn in the opposite direction. In the meantime, the driven gear does not impart directly the power to the driven shaft. Instead, the wheel hub is engaged with the driven gear so as to actuate the driven shaft. In the case of a prior art reverse gear device, the driven gear of the reverse set is united with a wheel hub capable of moving axially to engage or disengage. It is therefore readily apparent that the conventional reverse gear devices described above are large in volume and complicated in operation. Both the forward operation and the reverse operation of the conventional gear devices call for the engagement of two sets of gears, thereby resulting in mechanical wear, noise, and an increase in power loading. As a result, the engine of the motor scooter is vulnerable to damage and oil leak. In addition, the conventional reverse gear devices cannot be maintained economically.
The primary objective of the present invention is to provide a combined variable transmission system with a reverse gear device which is simple in construction, small in volume, and easy in maintenance. The reverse gear device comprises a drive bevel gear, a driven bevel gear, an idle bevel gear, an idle gear shaft, two shifting forks, and a sector plate cam. The drive bevel gear and the driven bevel gear are identical in specification with each other and are mounted respectively on two ends of a rear wheel axle on the basis of a toothed cone center. The drive bevel gear and the driven bevel gear are provided with a groove facing the center axis of the toothed cone. The drive bevel gear is mounted on the axle by means of a spline hole, while the driven bevel gear is mounted on the axle by means of a round hole, so as to facilitate the transmission of power in the usual forward motion. The idle bevel gear is smaller than the drive bevel gear and is mounted over the toothed cone center (right angle pitch of the center line of the axle). When the driven bevel gear is engaged in the reverse direction, the drive bevel gear and the idle bevel gear are actuated to displace by the sector plate cam and the two shifting forks, thereby resulting in engagement of the three bevel gears. The reverse motion is attained by the participation of the idle bevel gear in the change in the direction in which the driven bevel gear turns.
The features and the advantages of the present invention will be more readily understood upon a thoughtful deliberation of the following detailed description of the present invention with reference to the accompanying drawings.